Concrete placement apparatus

ABSTRACT

A concrete placer including a boom supported for pivotal movement on a horizontal pivot axis of a base with powered linkage means for pivoting the boom on the base. The powered linkage means includes a link having one end pivoted on the horizontal axis through a fluid motor interposed between the base and the link. A second fluid ram is pivotally connected to the link and the boom and the powered linkage means is arranged so that the boom can be pivoted about 180* about the horizontal pivot axis. The boom is of the articulated type having a plurality of sections with each adjacent pairs of sections being pivotally interconnected and having cooperating powered linkage means for pivoting adjacent pairs of sections from an overlapping relation to a substantially end-to-end relation. The boom sections support concrete transmission means which includes a conduit for each of the boom sections with the adjacent ends of the respective conduits interconnected by end pieces having a portion located on the pivot axis for the respective sections which accommodates pivotal movement of the sections.

United States Patent 1 Schaible et al. I

[ 1' Jan. 2, 1973 l 54] CONCRETE PLACEMENT APPARATUS [75] Inventors: Aaron M. Schaible, deceased, late of Rochester, Wis.; James F. Bremer, special administrator, Waterford, Wis.; Wilbur G. Braun, Waterford,

Wi Bernard rwmyetet otql Wisl Wilbur G. Bennett, Terre Haute; Richard L. Brown, Terre [52] U.S. Cl ..137/615, 137/565 [51] Int. Cl. ..B67d 5/36, B67d 5/60, B67d S/64 [58] Field of Search ..l37/6l5, 565; l4l/387, 388;

[57] ABSTRACT A concrete placer including a boom supported for pivotal movement on a horizontal pivot axis of a base with powered linkage means for pivoting the boom on the base. The powered linkage means includes a link having one end pivoted on the horizontal axis through a fluid motor interposed between the base and the link. A second fluid ram is pivotally connected to the link and the boom and the powered linkage means is arranged so that the boom can be pivoted about 180 about the horizontal pivot axis.

The boom is of the articulated type having a plurality of sections with each adjacent pairs of sections being pivotally interconnected and having cooperating powered linkage means for pivoting adjacent pairs of sections from an overlapping relation to a substantially end-to-end relation.

The boom sections support concrete transmission means which includes a conduit for each of the boom sections with the adjacent ends of the respective con- [56] Reerences Cited duits interconnected by end pieces having a portion UNITED STATES PATENTS located on the pivot axis for the respective sections which accommodates pivotal movement of the sec- 3,s72,3s0 3/1971 Jackson ..l37/6l5 n 3,22l,772 12/1965 Arntzen.... .....137/6l5 3,096,797 7/1963 Bily ..l37/6l5 3,217,748 ll/l965 Harper ..l4l/388 Primary Examiner-Alan Cohan 22 Claims, 8 Drawing Figures Assistant Examiner-'William H. Wright Attorney-Dressler, Goldsmith, Clement & Gordon and Blum, Moscovitz, Friedman & Kaplan I I 941 w f6 /'I/ I f! N/ if g 4&5 a,

PATENTEDJAN 2191s SHEET 1 OF 3 CONCRETE PLACEMENT APPARATUS BACKGROUND OF THE INVENTION The present invention relates generally to an apparatus for conveying fluent materials, such as concrete.

With the recent emphasis on the use of concrete for high rise building structures, various concrete pumps have been proposed for transporting a plastic mass, such as concrete, to a level a considerable distance above the ground. Such units are generally disclosed in U.S. Pat. Nos. Re. 26,820; 3,327,641; and 3,494,290.

While pumping units of this type have proven satisfactory in transmitting moist compressable materials to considerable heights, difficulties have been encountered in utilizing such units effectively since there was no manner of properly supporting the necessary hosing required for transmitting the materials any great distances. It will be appreciated that a material, such as concrete, is extremely heavy and, when placed in columnar form in a hose a height of more than 100 feet,

appropriate supporting equipment is necessary for the flexible hosing. While .support mechanisms for concrete have been proposed, see for example U.S. Pat. No. 3,367,280 and 3,409,334, these supporting units have not found any degree of commercial success because of the time and energy required for varying the effective length of the supporting unit.

SUMMARY OF THE INVENTION The present invention contemplates a concrete placement unit which includes an articulated boom that has a base section which is capable of being pivoted substantially 180 about a base with the base in turn capable of being rotated substantially 360 about a vertical pivot axis. The boom of the pumping unit of the present invention is constructed in a manner that the effective length thereof can readily be changed while concrete is being transmitted through the unit.

The concrete placer of the present invention includes a boom supporting base rotatable about a vertical pivot axis on a platform with a boom pivoted at one end about a horizontal axis on the base by powered linkage means. The powered linkage means includes a link having one end pivotally supported on the horizontal axis and first and second fluid rams respectively interposed between the base, the link and the boom. The fluid rams and link are arranged in a manner that the boom can be pivoted more than 90 about the horizontal axis. x

The boom, forming part of the concrete placer of the present invention, is of the articulated type and includes a plurality of boom sections with each pair of sections interconnected at adjacent ends for pivotal movement from a substantially overlapping position to a substantially end-to-end position. The means for pivoting the boom section relative to each other again includes powered linkage means having opposite ends connected to the respective sections.

According to another aspect of the invention, the boom supports concrete transmission means which is capable of having concrete transmitted therethrough while the boom sections are moved relative to each other. The concrete transmission means including a conduit for each of the plurality of boom sections and interconnecting means for adjacent ends of the respective conduits with the interconnecting means having a portion located on the pivot axis between adjacent pairs of sections. The interconnecting means include first and second end pieces each having a bend therein and portion of each end piece is located on the pivot axis between the sections. One end of each of the end pieces is connected to one of the conduits by releasable bracket means while the opposite ends of pairs of end pieces are interconnected to accommodate relative rotational movement of the respective ends. More specifically, the means for connecting the opposite ends of the respective end pieces includes flange means on one of the end pieces which defines an enlarged recess and a sleeve on the other of the end pieces with the sleeve being received in the enlarged recess and retained therein by a ring having a portion overlying a portion of the sleeve and the flange and being connected to the flange. Additionally, the connection between the end pieces and the respective conduits incorporates a quick-release connection so that the end piece can be readily separated from the conduit for cleaning either the end piece or the conduit.

The entire placement unit is constructed and arranged so that the unit may be attached to the frame of a conventional transporting unit or vehicle, such as a truck, after the unit has been assembled and is ready for use.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF DRAWINGS FIG. 1 is a side elevation view of a concrete placer of the present invention supported on a transport vehicle;

FIG. 1a is a side elevation of the boom in a collapsed condition;

FIG. 2 is a fragmentary plan view of a portion of the concrete transmission means;

FIG. 3 is an enlarged fragmentary view of the power linkage for the boom on the base;

FIG. 4 is an enlarged fragmentary sectional view taken generally along line 4-4 of FIG. 2;

FIG. 5 is a section view taken generally along line 5-5 of FIG. 4;

FIG. 6 is an enlarged fragmentary sectional view showing the releasable bracket means for interconnecting conduit sections; and

FIG. 7 is a sectional view taken generally along line 7 7 of FIG. 6.

DETAILED DESCRIPTION While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one specific embodiment, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated.

FIG. 1 of the drawings discloses a concrete placement unit, generally designated by the reference numeral 10. The concrete placement unit 10 is illustrated as of the self-propelled type and includes a vehicle, generally designated by the reference numeral 12, having a frame 14 supporting the various parts of the concrete placer. The concrete placer 16 includes a concrete pumping unit 16 and a concrete placement unit, generally designated at 20. Since the concrete pumping unit 18 forms no part of the present invention,

no detailed description thereof appears to be necessary. However, for purpose of completeness, US. Pat. No. 3,494,290 assigned to the assignee of the present invention, is incorporated herein by reference and discloses a concrete pumping unit which may be used with the present invention.

The concrete pumping unit 18 delivers concrete to an outlet conduit 22 which is connected to the placement unit through a flexible conduit 24.

The placement unit 20 includes a base supported for rotational movement about a vertical axis on a turntable 32 which is secured to the upper surface of the platform 34 and a boom 36 is supported for pivotal movement about a horizontal axis 38 on the base 30. The platform has a plurality of extensible outriggers 39 depending therefrom. The platform and Outriggers are arranged so that the entire placement unit 20 can be attached directly to the frame or chassis of a commercial truck, such as any 24,000 GVW or larger, without any modification of the chassis. This arrangement is of considerable importance since it reduces the overall cost of a self-propelled concrete placer.

According to one aspect of the present invention, the concrete placement unit 20 includes powered linkage interposed between the base 30 and the boom 36 for pivoting the boom substantially more than 90 about the horizontal pivot axis 38 on the base 30. Such an arrangement considerably increases the versatility of the unit.

The powered linkage means 40 includes a link 42 having one end pivoted about the pivot axis 38 for the boom .36. A first fluid ram 44 has its cylinder 46 pivotally secured at 48 to an extension of the base 30 while the piston rod 50 has its free end pivotally connected at 52 to the link 42. The powered linkage 40 further includes a second fluid ram 54 having its cylinder or first element 56 pivotally connected at 58 to the free end of the link while the piston rod or second element 60 of the ram is connected through a bracket 62 to the boom 36 at a location spaced from the pivot 38.

An inspection of FIGS. 1 and 1a reveals that the bracket 62 has a cradle portion (not shown) which has arms located on opposite sides of the boom and welded to the boom with spacer tubes 63 extending through the boom sides and the arm and welded to the arms to prevent collapsing of the boom section. The advantage of the bracket connection at the center of the boom rather than the bottom side of the boom is that the inner end of the moment arm, defined by the bracket 62, for the ram 54, is at the center of the boom. This ar rangement allows greater loads to be applied to the bracket without breaking the connection.

Referring particularly to FIG. 3, it will be noted that the pivotal connection 52 of the first fluid ram 44 to the link 42 is at a position intermediate the pivotal connection 38 of the link to the base 30 and the pivotal connection 58 of the second fluid ram to the link 42. FIG. 3 also shows that the horizontal spacing between the pivotal connection 38 and 48 is defined by a dimension A while the vertical spacing between these pivots is defined by a dimension C. Also, the spacing between pivots 38 and 52 is defined by a dimension B while the spacing between pivots 38 and 58 is defined by a dimension D which is greater than the dimension B. Additionally, the spacing between the pivotal connections 48 and 52 of the respective elements of the first fluid ram 44 defines a dimension E.

Applicants have determined that the particular dimensions between the various pivot points and the algebraic relationship of these dimensions to a large measure determines the successful operation of the fluid powered linkage means. Thus, according to a specific aspect of the present invention, the dimensions A, B, and C are substantially equal while the dimension E is less than either of these dimensions, on the order of one-half of the A, B, or C. In addition, the dimension D is substantially greater than the dimension B and is on the order of 1.5 times the dimension B.

By selecting the dimensions as described above, the effective moment arm for the first fluid ram will be substantially the same for both extreme positions of the link 42. In addition, the effective moment arm will be greater between the extreme positions. Also, the selection of the dimensions A, B, C' and E, as well as the length of stroke of the fluid ram 44 will have the link 42 pivoted approximately 90 about the pivot axis 38 as the link is moved from one extreme position to the other. The respective positions of the link are shown in the solid and dotted line positions of FIG. 3.

With the selection of dimensions as described above, the effective moment arm for the fluid arm 44 will be approximately the same for each extreme position of the link 42 so as to be capable of applying substantially the same forces to the boom during retraction of fluid ram 44 as is available during the extension.

Additionally, after the link 42 has been moved to the second extreme position shown by the dotted lines of FIG. 3, the second fluid ram 54 may likewise be extended to pivot the boom substantially 180 from the first or right-hand position shown in FIG. 3. Furthermore, the position of the link 42 will be such that the maximum moment arm for the second fluid ram will be available as the boom passes across the vertical axis defined by the turntable 32.

According to another aspect of the present invention, the concrete placement boom 36 is of the articulated type and preferably includes three sections, with adjacent pairs of sections having their adjacent ends pivotally interconnected and capable of being pivoted from a substantially overlapping, shown in FIG. 1a, to a substantially end-to-end relationship. The articulated boom vastly increases the versatility of the entire unit and greatly increases the performance of the concrete placing device 10.

Particular reference to FIGS. I and 1a the boom 36 includes a first or base section 36a, a second or intermediate section 36b and a third or outer end section 36c. The sections 360 and 36b have adjacent ends pivotally interconnected at and are moved from a substantially overlapping position shown in FIG. la, to a substantially end-to-end position by fluid powered linkage means 72. An inspection of FIG. 1 shows that the powered linkage means includes a fluid ram 74 having its cylinder 76 pivotally connected to the bracket 62 at 78 and its piston rod 80 connected to the pivotal connection 82 of a compound linkage including links 84 and 86. The free ends of the respective links 84 and 86 are pivotally connected to the boom sections 360 and 36b at locations spaced from the pivot 70. With this arrangement, a single fluid ram may be utilized to pivot the base and intermediate sections substantially 180 from an overlapping position to a substantially end-to-end position.

The intermediate or second boom section 36b is likewise pivotally connected to the boom section 36c by a pivotal connection 90 and again includes fluid powered linkage means 92 similar to linkage means 72 so that the outer end section 360 may be pivoted from an overlapping position shown in FIG. la to a substantially end-to-end position shown in FIG. 1.

According to another aspect of the present invention, a concrete placement unit includes a fluid transmission means which is completely separated from the boom 36 and which is capable of continuously transmitting concrete therethrough while the various boom sections are pivoted relative to each other. This arrangement of course allows for greater versatility of the machine since it is not necessary for the operator to discontinue the flow of concrete while the unit is being repositioned to supply concrete to a different location. For example, if a wall of a building were being poured, a skilled operator could readily manipulate the boom so as to traverse the entire length of the wall while concrete was continuously being delivered through the concrete transmission means.

The concrete transmission means includes a conduit for each of the boom sections and means for interconnecting the adjacent ends of the conduits to accommodate pivotal movement of the sections by the powered linkage means 72 or 92. Thus, with particular reference to FIGS. 1 and 2, the concrete transmission means includes a conduit 100 extending substantially the entire length of the outer end boom section 360, a second conduit 102 extending substantially the entire length of boom section 36b and a third conduit 104 extending substantially the entire length of the first boom section 36a. The respective conduits 100, 102 and 104 are supported on the associated boom sections by brackets 108, which may be of the two-piece type encompassing the associated conduit.

The concrete transmission means further includes interconnecting means 110 for connecting adjacent ends of respective pairs of conduits and accommodating pivotal movement of the boom sections. The interconnecting means is more clearly shown in FIG. 2 and includes first and second end pieces 112 each having a 90 bend therein. One end of each of the end pieces 112 is releasably connected to one end of a conduit by releasable bracket means 114, which will be described in more detail hereinafter. The opposite ends of the respective end pieces 112 have their axes aligned with the pivot axis between the respective boom sectioris, e.g. sections 36b and 36c, with means 116 interconnecting the opposite ends of the end pieces for accommodating relative rotational movement when the associated boom sections are pivoted relative to each other.

The interconnecting means 1 16 for the opposite ends of the two end pieces is more clearly shown in FIGS. 4 and 5 and includes flange means 120 fixedly secured to the end of one of the end pieces 112, as by welding. The flange means defines an enlarged recess 122 for receiving a sleeve 124 fixedly secured to the other end piece 112. The interconnecting or coupling means 1 16 further includes a retaining ring or means 126 for retaining the sleeve 124 in the recess 122. An inspection of FIG. 5 will show that the means 126 has portions overlying the sleeve 124 and the flange and is fixedly secured to the flange by a plurality of circumferentially spaced bolts 128. The sleeve 124 further has an end portion 130 of reduced diameter to define a further recess for receiving an O-ring 132 and a backup ring 134. A

Thus, the flange means 120 and the sleeve 124 cooperate to accommodate relative rotational movement of the end pieces 112 while the associated boom sections are pivoted relative to each other. The particular interconnecting means 116 is designed to be capable of having concrete transmitted therethrough while the associated boom sections are pivoted relative to each other. This feature is of extreme importance in increasing the efficiency of the overall machine since it eliminates the necessity of discontinuing the pumping of concrete while the boom is repositioned.

An inspection of FIG. 2 reveals the conduit 102 is located on one side of the intermediate boom section 36b while the conduits 100 and 104 are located on the opposite sides of the outer and inner boom sections 36c and 360. Furthermore, the connections between adjacent ends of the respective conduits, while having a portion aligned with the pivots 70 and 90, do not form any part of the structure defining the respective pivotal connections for the boom sections.

According to a further aspect of the present invention, each of the bracket means 114 are of the quick release type so that each of the end pieces 1l2'can readily be disconnected from the associated main conduit in instances when it is necessary to remove an end piece or a conduit because it is plugged with concrete. It will also be appreciated that such an arrangement considerably reduces the time required for removing and replacing any of the boom sections or end pieces.

The releasable bracket means 114 is shown more clearly in FiGS. 6 and 7 and includes circumferential recesses in the periphery of the conduits, e.g. 100 and 112, adjacent the ends thereof that receive respective legs 141 of a bracket which includes a first and second bracket portions 142 and 146 pivotally interconnected at 148. A sealing gasket 147 is received in each of the bracket portions 142 and 146 and the opposite ends of the bracket portions 142 and 146 are releasably connected by a releasable clamp 150 which normally locks the two portions 142 and 146. When locked together, the two portions emcompass the conduits .100 and 112 with the gaskets 147 engaging the periphery of the conduits adjacent the free ends to provide a fluid seal. However, the releasable clamp 150, can readily be opened by manipulation of a handle 154 so that the bracket portion 146 can be pivoted about pivot 148 to accommodate removal of either the end piece conduit'112 or the main conduits 100, 102 or 104.

The concrete placement unit 10 of the present invention, is an extremely compact unit in its collapsed condition (shown in FIG. 1a) and can be readily transported from one worksite to another over most major highways or other surface roads. When the unit arrives at a worksite, the boom or placement unit of the device can readily be manipulated into an operative position in a matter of minutes and will be ready for pumping concrete to various levels and different locations at the worksite without the necessity of assembling various sections as was heretofore necessary in placement units of the type disclosed in US. Pat. Nos. 3,367,280 and 3,409,334. It will be noted that the present concrete placement unit 20 of the invention is constructed in a manner that the concrete transmission means is completely separate from the boom structure and the rigidity of the boom structure is not in any way dependent upon any portion of the concrete transmission line. For example, the entire concrete transmission means could readily be removed from the boom structure and boom structure could be utilized for other purposes.

What is claimed is:

1. in a concrete placer, a boom supporting base rotatable about a vertical axis; a boom having one end pivotally supported about a horizontal axis on said base; a link having one end pivoted about said horizontal axis; a first fluid ram having first and second elements respectively pivotally connected to said base and said link; and a second fluid ram having first and second elements respectively pivotally connected to said link and said boom at a location spaced from said horizontal pivot axis, said link and rams being arranged so that extension of said rams pivot said boom substantially more than 90 about said horizontal axis.

2. A concrete placer as defined in claim 1, in which said second ram is connected to said link adjacent an opposite end and said first ram is connected to said link intermediate said ends.

3. A concrete placer as defined in claim 2, in which said first fluid ram pivots said link between first and second positions and defines an effective moment for said first fluid ram about said horizontal axis the further improvement of the effective moment of said first fluid ram being of substantially equal dimension in said positions and being greater between said positions.

4. A concrete placer as defined in claim 1, in which said boom includes at least two articulated sections having adjacent ends pivotally interconnected and further including fluid linkage means for pivoting said sections from an overlapping relation to a substantially end-to-end relation.

5. A concrete placer as defined in claim 4, including the further improvement of a concrete transmission conduit for each of said sections; and means for interconnecting adjacent ends of said conduits to accommodate pivotal movement of said sections.

6. A concrete placer as defined in claim 5, further including releasable bracket means for interconnecting said conduits on the respective boom section.

7. A concrete placer as defined in claim 6, in which said releasable bracket means each, include first and second bracket portions encompassing said conduits and pivotally interconnected on one side thereof; and clamp means releasably connecting on opposite sides of said portions.

8. A concrete placer as defined in claim 5, in which said conduits are respectively located on opposite sides of associated sections and in which said means for interconnecting said adjacent ends includes first and second end pieces, each having a bend and having one end cooperating with one of said conduits, said end pieces having opposite ends with the axes of said opposite ends aligned with the pivotal interconnection between said boom sections.

9. A concrete placer as defined in claim 8, further including flange means defining an enlarged recess on the opposite end of one of said end pieces and an enlarged sleeve on the opposite end of the other of said end pieces, said sleeve being received in said recess; and ring means attached to said flange means, said ring means overlapping said sleeve to interconnect said end pieces and accommodate rotational movement about said pivot.

10. A concrete placer as defined in claim 1, in which said boom has a longitudinal axis, and further including bracket means extending to one side of said boom with said second element of said second fluid ram pivotally connected to said bracket means at a location spaced from said one side; and connecting means connecting said bracket to said boom along the longitudinal cen-v terline of said boom so that forces transmitted from said second ram are transmitted to said boom substantially along said longitudinal centerline.

11. A concrete placer as defined in claim 1, in which said boom includes three sections with adjacent ends of said sections pivotally interconnected; fluid linkage means cooperating with adjacent sections to pivot adjacent sections from an overlapping position to a substantially end-to-end position; and concrete transmission rneans for said boom, said transmission means including first, second and third conduits with the second conduit located on one side of the second section and the first and third conduits located on a side of first and third sections which is opposite said one side of said second boom section; and means for interconnecting adjacent ends of respective conduits, said last means having a portionlocated on the pivot axis between respective sections to accommocate pivotal movement of said sections.

12. A concrete placer as defined in claim 1, in which the horizontal and vertical dimensions between the horizontal axis and said pivotal connection between the base and the first fluid ram are substantially equal, and the spacing between the pivotal connections of said elements of said first fluid ram is less than said dimensions when said link is in a first position.

13. A concrete placer as defined in claim 12, in which the spacing between the horizontal pivot axis and the pivotal connection between the first fluid ram and said link is substantially equal to said dimensions and in which the spacing between the horizontal axis and the pivotal connection between the link and the second fluid ram is greater than said dimensions.

14. A concrete placer as defined in claim 1, further including a platform supporting said base; and a plurali ty of extensible Outriggers depending from said platform, said platform and Outriggers being arranged so that said platform may be connected to a frame of a vehicle.

15. A concrete placer comprising a base; a boom pivoted about a horizontal axis on said base, said boom including a plurality of boom sections with adjacent pairs of said sections being pivotally interconnected, each boom section having opposed side walls; powered linkage means for pivoting said boom on said base and pivoting said sections relative to each other; and concrete transmissionmeans for said boom and including a separate rigid conduit for each of said sections; one conduit for one boom'section of said pair being located on one side of the associated boom section and the conduit associated with the next boom section being located on the opposite side of the next boom section, each conduit being separate from its associated boom section and being located beyond the adjacent side wall; and means for interconnecting adjacent ends of adjacent conduits, said last means including a portion located on the pivot axes for the respective pairs of section, said portion accommodating pivotal movement of said sections.

16. A concrete placer as defined in claim 15, in which said last means includes first and second end pieces for each pivotal connection between the conduits of adjacent boom sections, each end piece having a 90 bend and one end connected to one conduit; and means interconnecting the opposite ends of the first and second end pieces for accommodating relative rotational movement.

17. A concrete placer as defined in claim 16, in which said last means each include flange means on one of said first and second end pieces and defining an enlarged recess; a sleeve on the other of said first and second end pieces and received in said recess; and means for retaining said sleeve in said recess.

18. A concrete placer as defined in claim 16, further including quick release bracket means for interconnecting said one end of each end piece with a conduit,

said bracket means each comprising first and second bracket portions pivotally interconnected and cooperating to encompass said conduit and said one end, and a releasable clamp retaining said portions around said conduit and said one end.

19. A concrete placer as defined in claim 15, further including a platform supporting said base, a vehicle having a frame normally supporting said platform; and a plurality of outriggers carried by said platform, said Outriggers being extensible to raise said platform above said frame so that said platform may be attached to said frame.

20. A concrete placer as defined in claim 16, in which said connection between said one end of each end piece and a conduit includes an enlarged portion on said one end and the adjacent end of the conduit and bracket means encompassing said enlarged portions.

21. A concrete placer as defined in claim 15, in which said powered linkage means between said base and said boom includes a link having one end pivoted about said horizontal pivot axis, a first fluid rarn interposed'between said base and said link and a second fluid ram interposed between said link and a first section of said boom, said rams and link being arranged so that said boom may be pivoted substantially about said horizontal axis.

22. A concrete placer as defined in claim 21, in which said second fluid ram is pivotally connected to an opposite end of said link and said first fluid ram is connected to said link intermediate its ends. 

1. In a concrete placer, a boom supporting base rotatable about a vertical axis; a boom having one end pivotally supported about a horizontal axis on said base; a link having one end pivoted about said horizontal axis; a first fluid ram having first and second elements respectively pivotally connected to said base and said link; and a second fluid ram having first and second elements respectively pivotally connected to said link and said boom at a location spaced from said horizontal pivot axis, said link and rams being arranged so that extension of said rams pivot said boom substantially more than 90* about said horizontal axis.
 2. A concrete placer as defined in claim 1, in which said second ram is connected to said link adjacent an opposite end and said first ram is connected to said link intermediate said ends.
 3. A concrete placer as defined in claim 2, in which said first fluid ram pivots said link between first and second positions and defines an effective moment for said first fluid ram about said horizontal axis the further improvement of the effective moment of said first fluid ram being of substantially equal dimension in said positions and being greater between said positions.
 4. A concrete placer as defined in claim 1, in whiCh said boom includes at least two articulated sections having adjacent ends pivotally interconnected and further including fluid linkage means for pivoting said sections from an overlapping relation to a substantially end-to-end relation.
 5. A concrete placer as defined in claim 4, including the further improvement of a concrete transmission conduit for each of said sections; and means for interconnecting adjacent ends of said conduits to accommodate pivotal movement of said sections.
 6. A concrete placer as defined in claim 5, further including releasable bracket means for interconnecting said conduits on the respective boom section.
 7. A concrete placer as defined in claim 6, in which said releasable bracket means each, include first and second bracket portions encompassing said conduits and pivotally interconnected on one side thereof; and clamp means releasably connecting on opposite sides of said portions.
 8. A concrete placer as defined in claim 5, in which said conduits are respectively located on opposite sides of associated sections and in which said means for interconnecting said adjacent ends includes first and second end pieces, each having a 90* bend and having one end cooperating with one of said conduits, said end pieces having opposite ends with the axes of said opposite ends aligned with the pivotal interconnection between said boom sections.
 9. A concrete placer as defined in claim 8, further including flange means defining an enlarged recess on the opposite end of one of said end pieces and an enlarged sleeve on the opposite end of the other of said end pieces, said sleeve being received in said recess; and ring means attached to said flange means, said ring means overlapping said sleeve to interconnect said end pieces and accommodate rotational movement about said pivot.
 10. A concrete placer as defined in claim 1, in which said boom has a longitudinal axis, and further including bracket means extending to one side of said boom with said second element of said second fluid ram pivotally connected to said bracket means at a location spaced from said one side; and connecting means connecting said bracket to said boom along the longitudinal centerline of said boom so that forces transmitted from said second ram are transmitted to said boom substantially along said longitudinal centerline.
 11. A concrete placer as defined in claim 1, in which said boom includes three sections with adjacent ends of said sections pivotally interconnected; fluid linkage means cooperating with adjacent sections to pivot adjacent sections from an overlapping position to a substantially end-to-end position; and concrete transmission means for said boom, said transmission means including first, second and third conduits with the second conduit located on one side of the second section and the first and third conduits located on a side of first and third sections which is opposite said one side of said second boom section; and means for interconnecting adjacent ends of respective conduits, said last means having a portion located on the pivot axis between respective sections to accommocate pivotal movement of said sections.
 12. A concrete placer as defined in claim 1, in which the horizontal and vertical dimensions between the horizontal axis and said pivotal connection between the base and the first fluid ram are substantially equal, and the spacing between the pivotal connections of said elements of said first fluid ram is less than said dimensions when said link is in a first position.
 13. A concrete placer as defined in claim 12, in which the spacing between the horizontal pivot axis and the pivotal connection between the first fluid ram and said link is substantially equal to said dimensions and in which the spacing between the horizontal axis and the pivotal connection between the link and the second fluid ram is greater than said dimensions.
 14. A concrete placer as defined in claim 1, further including a platform supporting said base; and a plurality of extensible outriggers depending from said platform, said platform and outriggers being arranged so that said platform may be connected to a frame of a vehicle.
 15. A concrete placer comprising a base; a boom pivoted about a horizontal axis on said base, said boom including a plurality of boom sections with adjacent pairs of said sections being pivotally interconnected, each boom section having opposed side walls; powered linkage means for pivoting said boom on said base and pivoting said sections relative to each other; and concrete transmission means for said boom and including a separate rigid conduit for each of said sections; one conduit for one boom section of said pair being located on one side of the associated boom section and the conduit associated with the next boom section being located on the opposite side of the next boom section, each conduit being separate from its associated boom section and being located beyond the adjacent side wall; and means for interconnecting adjacent ends of adjacent conduits, said last means including a portion located on the pivot axes for the respective pairs of section, said portion accommodating pivotal movement of said sections.
 16. A concrete placer as defined in claim 15, in which said last means includes first and second end pieces for each pivotal connection between the conduits of adjacent boom sections, each end piece having a 90* bend and one end connected to one conduit; and means interconnecting the opposite ends of the first and second end pieces for accommodating relative rotational movement.
 17. A concrete placer as defined in claim 16, in which said last means each include flange means on one of said first and second end pieces and defining an enlarged recess; a sleeve on the other of said first and second end pieces and received in said recess; and means for retaining said sleeve in said recess.
 18. A concrete placer as defined in claim 16, further including quick release bracket means for interconnecting said one end of each end piece with a conduit, said bracket means each comprising first and second bracket portions pivotally interconnected and cooperating to encompass said conduit and said one end, and a releasable clamp retaining said portions around said conduit and said one end.
 19. A concrete placer as defined in claim 15, further including a platform supporting said base, a vehicle having a frame normally supporting said platform; and a plurality of outriggers carried by said platform, said outriggers being extensible to raise said platform above said frame so that said platform may be attached to said frame.
 20. A concrete placer as defined in claim 16, in which said connection between said one end of each end piece and a conduit includes an enlarged portion on said one end and the adjacent end of the conduit and bracket means encompassing said enlarged portions.
 21. A concrete placer as defined in claim 15, in which said powered linkage means between said base and said boom includes a link having one end pivoted about said horizontal pivot axis, a first fluid ram interposed between said base and said link and a second fluid ram interposed between said link and a first section of said boom, said rams and link being arranged so that said boom may be pivoted substantially 180* about said horizontal axis.
 22. A concrete placer as defined in claim 21, in which said second fluid ram is pivotally connected to an opposite end of said link and said first fluid ram is connected to said link intermediate its ends. 